1. Field of the Invention
The present invention relates to an auxiliary filtration system and a method of continuous filtration in engine applications.
2. Background Art
Current oil filtration systems for vehicle engines consist of a full flow filter in which 100% of the engine oil flow passes through the filter. The filter is designed to remove only the large particles from the oil because the filter must not restrict the oil flow. In turn, the filtering effectiveness is extremely limited. Current full flow filters are only efficient in controlling particles fifteen microns and larger. Ninety-five percent of the contamination generated within a vehicle engine is smaller then ten microns. This current filtration technology leads to short oil change intervals. Frequent oil changes are expensive, time consuming, and generate a tremendous amount of waste from the disposal of oil and oil filters. Most full flow filters are also equipped with a bypass valve. These filters have a tendency to clog before the service interval is up. When this happens, the bypass valve opens and unfiltered oil is circulated throughout the engine.
To add to the dilemma, increasingly stringent air emission regulations have dictated new engine designs employing the use of exhaust gas re-circulation (EGR) technology. EGR systems send a portion of the engine exhaust gas back to the combustion chamber in order to reduce NOx formation; however, EGR causes an increase in the amount of soot being deposited to the oil. Soot is a by-product of the combustion process and its primary component is carbon. These soot particles are very small; they are hard, abrasive and have a tendency to bind or stick together to form larger masses of soot. High soot levels in the engine oil will cause an increase in the oil viscosity, which then leads to higher operating temperatures. High soot levels will also result in the early depletion of the chemical additives in the oil which prevent oil deterioration. This leads to excessive engine wear and reduction in engine life. Finally, the large masses of soot can cause premature filter plugging. EGR provides a multi-pass opportunity for soot to enter the oil. Because of the new engine designs, especially the trend to use EGR in diesel engines, the oil is getting dirtier faster.
The industry""s solution thus far has been the adaptation of bypass filter systems. The bypass filter system is typically installed in parallel to the full flow filter. The bypass filter continuously diverts a side stream of ten to fifteen percent of the engine oil flow, filters it more efficiently through the use of finer filtration, and then returns the oil back to the oil pan. The bypass filter works in conjunction with the full flow filter to capture particles and contamination that are missed by the full flow filter. When the full flow filters are run in parallel with the bypass filters, they have less work to do, thereby increasing the time between service intervals. However, the bypass filters do have limitations. Current bypass filters can capture particles in the range of five to twenty microns. This leaves many smaller and more abrasive particles suspended in the oil. One particularly harmful contaminant that remains unfiltered is soot. Soot particles are typically less than one micron in size and have a tendency to stick together or agglomerate over time. Soot agglomerates grow in size until they fall out of suspension and form sludge in the bottom of the oil pan. Because of the limited filtering capacity associated with the canister designs of current bypass filters, sludge causes premature clogging of both the full flow and bypass filters. With more soot being deposited in the oil due to EGR, this becomes an even greater concern. One final problem associated with bypass filter systems is the introduction of lube pressure parasitic losses. Because bypass systems divert approximately ten percent of an engine""s total oil stream to the bypass filter, a lube pressure parasitic loss is introduced. In extreme conditions, diversion of this amount of oil can lead to starvation of necessary lubrication in certain engine components.
The use of a high efficiency bypass filtration system is not a complete answer to the problems that plague the industry. In order to extend oil and filter life, it is necessary to adopt a system that incorporates the advantages of a by-pass system with the ability to extend oil filtering capacity.
The present invention utilizes an auxiliary filtration system in conjunction with a continuous filtering method. The auxiliary filtration system operates totally independent of the main lubrication system of an engine and consists of a pump, a filtration device, and the appropriate hardware and fluid conductors. These components are installed as a separate sub-system of a vehicle engine""s conventional lubrication system. The pump pumps the oil out of the oil pan, through the filtration device, and back to the oil pan in a continuous fashion. The pump flow is variable and relatively low to allow for the efficient removal of small particles. The auxiliary filtration unit is relatively easy to retrofit on existing engine systems and allows for extra oil capacity as well as off-line filtration. Oil cooling may also be incorporated into the system. The auxiliary filtration system can be used in the oil drain and fill process via the use of the pump, such as an electric oil pump, working in concert with the appropriate fluid conductors and valves or quick connect fluid conductors. During the oil drain, the oil will be pumped from the oil pan to an appropriate container. During the oil fill, the oil will be pumped from a container to the oil pan and can be sent through the filtration device to pre-filter the oil. The filtration system described herein may also be designed to be used as a replacement for the conventional full flow filter system.
The present invention utilizes an auxiliary filtration device to provide a continuous filtering method to the engine oil. This device consists of a replaceable/recyclable filtering media cartridge, a self-indexing system to continuously advance in clean filtering media, and a housing to enclose it all. The media cartridge contains filtering media, a supply reel and a take-up reel. It is also possible to design the auxiliary filtration system so that it does not contain a media cartridge. In this alternative embodiment, the filter media would be attached directly to the media reels in the filtration device housing.
The present invention applies a continuous filtering method to the engine oil. By using a reel-to-reel configuration, the filtration device is able to automatically replace used or dirty filtering media with clean filtering media in a controlled and continuous fashion. The invention provides an unlimited filtering capacity for contaminant retention over a set service interval. Because of this continuous method, the filtering operation will be unaffected by the high soot levels introduced from EGR. The reel-to-reel principle is based upon the monitoring of the pressure differential between the upstream side and the downstream side of the filtering media. When a high pressure differential exists, due to the build up of particles on the filtering media, signals will be sent to the pumping means to cease oil flow to the filter, and to the self-indexing system to advance clean filtering media from a supply reel. At the same time, the self-indexing system will eject the dirty filtering media to a take-up reel. The pumping means then initiates oil flow back through the filter device. This process is continued until a desired pressure differential is attained. When the desired service interval has been reached, the filtering media cartridge can be removed and replaced with a new cartridge.
The present invention utilizes high efficiency finer filtration to capture more soot and suspended particles than both the conventional full-flow and bypass filters. Additionally, since the auxiliary filter is filtering solid contaminants at a much finer level than the full flow filter, the full flow filter does not become prematurely clogged and its life is extended.
Electrostatic agglomeration can be incorporated into the invention to enhance the invention""s ability to capture small, problematic contaminants such as soot. This could be accomplished by either placing an electrically charged wire mesh in front of the filtering media or fabricating it into the filtering media. The charged mesh would allow for the attraction and agglomeration of soot particles onto the mesh. Once the agglomerates reach a certain size, the oil flow will cause the agglomerates to break off and be collected by the filtering media. A second alternative method of soot collection utilizes a special chemical coating to enhance the filtering media and its ability to attract and collect soot particles.
The filtration device can also be designed to replenish the oil with additives. One means of accomplishing additive replenishment would be to monitor the quality of the oil, and when it is determined that replenishment is necessary, use an injector to spray additives onto the filtering media or apply a special additive chemical coating to the filtering media. In both cases, the additives would dissolve into the oil flow as it passes through the filter media. Another alternative method of additive replenishment would involve mounting a replaceable and recyclable additive releasing cartridge onto the return line. The additives would dissolve into the oil flow as it passes through the cartridge.
An alternative embodiment of the invention would be an auxiliary filtration system described herein that does not include a pump. Instead of using an auxiliary pump to pump the oil to and from the oil pan through the auxiliary filtration system, it would be possible to simply divert a side stream of oil from the standard engine lubrication system to the auxiliary filter. The auxiliary filter would be mounted in parallel with the full flow filter.
Accordingly, an object of the invention is to provide an improved engine oil filtration system which includes an auxiliary filter operatively connected to an engine oil pan for selectively filtering fine contaminants from the oil, wherein the auxiliary filter preferably consists of a replaceable/recyclable filtering media cartridge including a self-indexing system to continuously advance clean filtering medium as the filtering media becomes clogged.
The above object and other objects, features and advantages of the invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.